For 747, transporting a shuttle is no heavy burden

By Larry Shaughnessy, CNN Pentagon Producer

Updated 7:14 AM ET, Wed April 18, 2012

Photos: Discovery flies into retirement15 photos

Space shuttle Discovery flies into retirement – Space shuttle Discovery, mounted atop a 747 shuttle carrier aircraft, goes by the Washington Monument during a flyover of the nation's capital on its trip to retirement Tuesday, April 17. The flight -- the last time Discovery will be aloft -- took it from Florida's Kennedy Space Center to the Washington area, where it will spend retirement as a museum piece at an annex to the Smithsonian National Air & Space Museum in Chantilly, Virginia, near Dulles International Airport.

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Photos: Discovery flies into retirement15 photos

Space shuttle Discovery flies into retirement – Discovery and its 747 jumbo jet carrier pass over the Smithsonian National Air and Space Museum annex in Chantilly, Virginia, on Tuesday. The shuttle will be removed from the modified jet and star as the guest of honor at a four-day celebration punctuated by a ceremony Thursday formally welcoming Discovery to the Smithsonian collection.

Space shuttle Discovery flies into retirement – Discovery flies over the National Mall on Tuesday as it arrives from Kennedy Space Center in Florida. The space shuttle Enterprise, which has been on display at the Smithsonian's Steven F. Udvar-Hazy Center since 1985, will be moved to the Intrepid Sea, Air & Space Museum in New York.

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Photos: Discovery flies into retirement15 photos

Space shuttle Discovery flies into retirement – Schoolchildren on a tour watch as Discovery flies over the U.S. Capitol on Tuesday.

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Space shuttle Discovery flies into retirement – Discovery makes a low pass over the Washington, D.C., area before its final landing Tuesday.

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Space shuttle Discovery flies into retirement – An aspiring astronaut poses in the parking lot of the Smithsonian National Air and Space Museum Steven F. Udvar-Hazy Center on Tuesday in Chantilly.

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Photos: Discovery flies into retirement15 photos

Space shuttle Discovery flies into retirement – Discovery flies over the National Mall before being retired at the Udvar-Hazy Center.

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Photos: Discovery flies into retirement15 photos

Space shuttle Discovery flies into retirement – People gather to watch the arrival of Discovery at the Smithsonian National Air and Space Museum Steven F. Udvar-Hazy Center on Tuesday in Chantilly.

Space shuttle Discovery flies into retirement – Special guests watch the Discovery's arrival from the observation deck of the Smithsonian National Air and Space Museum Steven F. Udvar-Hazy Center on Tuesday in Chantilly.

Story highlights

The load is not as taxing on the specially outfitted 747 as you might first think

A regular 747 carrying a full complement of passengers is much heavier

It was a strange sight indeed -- one large aircraft carrying another large aircraft strapped on top. But that's exactly what skyward-looking folks in Washington saw Tuesday as Space Shuttle Discovery, atop a Boeing 747, made an inspiring pass over the capital in its final flight.

It makes you wonder: How can the 747 transport something that big and heavy? Well, the shuttle-airliner combo is not as heavy as you might first think. In fact, it's a relatively easy load to hoist.

When the shuttle missions started in the 1980s, NASA designated several places as landing strips for the orbiter, including Edwards AFB in California.

But all the launches were from Florida, so NASA needed a way to transport to Kennedy Space Center from Edwards. A shuttle can't fly itself after it leaves orbit, as it is basically a big glider. So NASA created the designed the Shuttle Carrier Aircraft, which is a Boeing 747 designed to fly with a shuttle on top.

All that's well-known, at least to space buffs. But what may surprise many people is that a Boeing 747 with a space shuttle strapped on its roof weighs less -- that's right, less -- than a 747 airliner full of passengers.

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Space shuttle Discovery retires

At first that might seem counterintuitive, but Lisa Malone, a spokeswoman for NASA, says the 747 they use is stripped clean of anything in the main cabin. There's a cockpit and a big empty shell.

But the 747s used by airlines have hundreds of seats, galleys, lavatories -- even a bar in some cases. Add 300-plus passengers, their luggage, food, water and assorted other cargo, and the weight adds up.

The 747 that carried Discovery weighed about 488,000 pounds. Jim Proulx, a spokesman for Boeing, says a commercial 747 airliner can weigh more than 800,000 when carrying passengers.

There will be another chance to see the Shuttle Carrier Aircraft in action later this week. That's when it will carry Space Shuttle Enterprise, which was used for tests but never flew in space, will be flown from Dulles International Airport in Virginia to its new home on board the USS Intrepid, a retired aircraft carrier turned floating museum in New York City.